The wiggling structure observed in molecular outflows has been interpreted and successfully modeled in terms of variability of the ejection direction [1]}, [2]}, [3]}, [4]}, [5]}. Several
theoretical models have been proposed to explain this phenomenon [6]}, [7]}, [8]} but direct observational constraints are still lacking. It seems however that most of the identified precessing jets arise from multiple protostellar systems, which suggests that the presence of companion(s) probably plays a role in the origin of the phenomenon. The precession periods derived towards Class 0/I objects range from \(\sim 400\hbox{\hspace{1.99997pt}yr}\)  to 5\(\times 10^4\hbox{\hspace{1.99997pt}yr}\)  [8]}.
